The effect of superplasticity on the solid state weldability of the titanium alloy Ti-4. 5Al-3Mo-1V

The systematic study of solid state joint (SSJ) formation under conditions of hot and superplastic (SP) deformation by the mode of uniaxial tensile elongation and during vacuum annealing has been conducted. The two-phase VT14 alloy (Ti-4.5Al-3Mo-1V) with the initial microcrystalline and coarse-grained lamellar structure was taken for investigations. It has been established that deformation processes are mainly responsible for the formation of a sound joint. Annealing at the temperature of SP deformation does not increase the shear strength of joints in the samples with the initial strength of 0.4 of that of the base alloy. The considerable effect of SP deformation rate on the kinetic of SSJ formation has been revealed and it is noted that the formation of SSJ is mostly accelerated during deformation in the SP (optimum) Region 2. The given experimental results show that the acceleration of sound joint formation in the SP state is attributed to the influence of grain boundary sliding (GBS), the main mechanism of SP deformation.